Most likely it is time, but it depends on how much use you have on your bike.

They will tighten or replace cables and cable housing so your bike shifts smoothly, check to see if you chain has stretched, replace brake pads, true wheels, etc. Most people would get their bikes tuned once a year. Taking good care of your bike will minimize the frequency required.

Since I bought my new bike recently, I take serious advantage of the free tune-ups that the bike shops give for the first year since purchase. I take mine in about every 3 months or so, just cause I can. After that, I regularly check on the chain, etc. on my own, but tune up maybe once every 18 months or so.

personally i advocate a "basic" tune up 1 time a year if you ride your bicycle with any regularity.

if you are more of a serious enthusiast or triathlete or cyclist that rides consistenly during the season in bad and good weather, and especially if you ride in some serious wet wether i suggest a "full overhaul" on your bike 1 time a year that is basicallly like they rebuidl your bike with new cables/ repack the bearings with new grease, etc, then it runs like new and when i say that i literally mean it does feel as good as the day you first got the bike. however, overhauls genearlly run about 200-300 but they literlally do make the bike run like new, hardest part is finding a shop with "great mechanics" that does this job correctly, most shops cut corners and do not do the job correctly and charge you for work that they did not do. i wont' go into that now.